The present invention relates to the field of bicycle training apparatus; more specifically, it relates to roller system bicycle trainers.
A conventional bicycle roller system is a training device for bicyclists typically consisting of three parallel cylindrical rollers supported horizontally in a frame. One roller is positioned below the front wheel of the bicycle and two are positioned below the driven rear wheel. The two rear rollers are placed such that the rear wheel is cradled between them and in contact with both rear rollers at once. The front roller is linked to one of the rear rollers so that when a bicycle is ridden upon the system, both wheels of the bicycle spin at the same speed and impart stability to the bicycle via gyroscopic inertia. Such a bicycle roller system is described in U. S. Pat. No. 581,835 to Sturgis. This inertia allows the bicycle to be maintained in an upright position, but does little to limit lateral movement on the roller system. Minimal deviation of the front wheel from a straight-ahead orientation or a slight shift of the bicycle rider""s weight, causes relatively large lateral movement of the bicycle as compared to a bicycle on the ground. This potential for lateral movement and its sensitivity to rider input make rollers an excellent training device to improve bicycle handling skills, but severely limit their use for cardiovascular fitness. The average rider is constantly at risk of riding off the side of the rollers, as is an accomplished bicyclist should he become fatigued and lose concentration while riding. One solution to the problem of riding off the sides of the rollers is described in U.S. Pat. No. 463,862 to Guignard which employs concave rollers. Concave rollers in which the concavity is minimal (i.e., rollers having a shallow curvature) offer little aid in keeping the bicycle centered upon the roller. Concave rollers in which the concavity is severe (i.e., rollers having a deep curvature) reduce the skill-training benefit of rollers, while giving the sensation of riding down into a groove in the ground.
In addition, the uniform diameter rollers used by most conventional systems, carry little angular momentum. Thus, when the rider stops pedaling, the wheels stop in a matter of seconds and all gyroscopic-inertia helping to balance the bicycle is lost. This makes dismounting without falling difficult. A solution to the de-mounting problem is described in U.S. Pat. No. 3,905,597 to Tabb, which describes elevated and inwardly slanted platforms located adjacent to the pedaling region and positioned to be readily reached by the feet of the bicycle operator when the bicycle is in an upright operating position. However, the presence of such platforms can in itself present additional safety and convenience problems.
Because of the above difficulties, bicycle roller use is usually limited to skill training by accomplished riders.
This patent describes a bicycle roller system of the three-roller type, using rollers of a novel design. Each of the rollers comprises a xe2x80x9cflatxe2x80x9d (right-cylindrical) middle portion or central span of a first diameter, two end portions of a second diameter larger than the first diameter and two transitional portions, which are between the middle portion and each of the end portions. The transitional portions increase in diameter from the middle portion toward the ends of the roller. The transitional portions preferably have a curvilinear profile and an identical profile at both ends of a roller. The most preferred rate of increase of diameter of the transitional portions is a parabolic rate; i.e., the diameter is a parabolic function of distance measured along a direction parallel to the roller axis. Another equivalent way of characterizing the preferred shape of the transitional portion is to define it as paraboloidal. The rollers also preferably have disks of a relatively high density mounted at one or more ends as disk-shaped weights. The middle portion or central span of each roller, being of uniform diameter, allows skill training and as realistic a feel as on a system employing conventional flat rollers. The parabolic rate of increase in the diameter of the transitional portions of the rollers yields multiple benefits. First, the transitional portions impart a centralizing force to the bicycle tires when the tires leave the central span. This centralizing force increases the closer the tires come to the end of the roller, making it difficult to ride off the rollers. At a given rotational speed, the roller having a disk-shaped weight affixed at the end of the roller has greater angular momentum than a standard unweighted roller of lesser diameter, without requiring the entire roller to be of large diameter and without requiring massive weight to be used in small diameter rollers. The increased angular momentum or flywheel effect allows a rider to coast on the rollers, simulating actual ground riding. The flywheel effect also allows a rider time to start dismounting, i.e., to disengage his foot from a bicycle pedal and place the foot upon the supporting surface mounted under the bicycle, before the gyroscopic-inertia from the spinning wheels, which helps balance the bicycle, is lost. The rate of increasing diameter of the three rollers transitional portions can vary, even within a single system, as can the widths of the rollers and the widths of the xe2x80x9cflatxe2x80x9d middle portions. Specifically, if the transitional portions"" diameters vary in the preferred parabolic manner, the parabolic rates of increase of the diameter of the transitional portions can vary